Circulating platelet-derived and placenta-derived microparticles expose Flt-1 in preeclampsia.
BACKGROUND
Flt-1 is secreted by various cells and elevated concentrations are present in preeclampsia affecting vascular function. Microparticles from these cells may expose Flt-1. We evaluated whether Flt-1 is microparticle-associated in preeclampsia, and established the origin of Flt-1-exposing microparticles.


METHODS
The concentration of Flt-1 was measured in samples from preeclamptic patients, pregnant and nonpregnant women by enzyme-linked immunosorbent assay. Microparticles were analyzed by flow cytometry. Western blot determined the different forms of Flt-1.


RESULTS
Noncell bound Flt-1 was elevated in preeclampsia compared to controls. A fraction (5%) was associated with microparticles in preeclampsia. Flt-1-exposing microparticles were increased in preeclampsia compared to normotensive pregnancy (p = 0.02). Full-length Flt-1, was identified in microparticles of platelet and placental origin.


CONCLUSIONS
Full-length Flt-1 is associated with platelet and placenta-derived microparticles. Possibly, the presentation of Flt-1 on the membrane of a microparticle might alter its function, particularly if it acts in synergism with other exposed vasoactive molecules.
Lok
Christine A R
CA
Department of Obstetrics and Gynaecology, Academic Medical Center, Amsterdam, Netherlands. c.a.lok@ amc.uva.nl
Böing
Anita N
AN
Sargent
Ian L
IL
Sooranna
Suren R
SR
van der Post
Joris A M
JA
Nieuwland
Rienk
R
Sturk
Augueste
A
D000328:Adult; D001792:Blood Platelets / Q000378:metabolism*; D055252:Cell-Derived Microparticles / Q000378:metabolism*; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D010920:Placenta / Q000378:metabolism*; D011225:Pre-Eclampsia / Q000097:blood*; D011247:Pregnancy; D040281:Vascular Endothelial Growth Factor Receptor-1 / Q000097:blood*
C501162:FLT1 protein, human; D040281:Vascular Endothelial Growth Factor Receptor-1